Topological Anionic Confinement Enables Mild-Synthesis of 2D High-Entropy Molybdates

Two-dimensional (2D) high-entropy materials (HEMs) offer vast opportunities, yet their low-temperature synthesis with compositional homogeneity and anisotropic morphology remains a significant challenge, due to thermodynamic competition between entropy-driven mixing and strain-induced phase segregation. Here, we report a topological anionic confinement (TAC) strategy that employs MoO ₄ ²⁻ tetrahedra as spatially defined scaffolds to effectively suppress cation segregation. This strategy enables the single-step, template-free synthesis of a novel series of 2D high-entropy molybdate assemblies (M ₃ (MoO ₄ ) ₄ ·4H ₂ O, M = Mn, Fe, Co, Ni, Cu, Zn) at 120 °C. In situ liquid-phase transmission electron microscopy unveils a non-classical crystallization pathway, where metastable clusters undergo dissolution-regrowth for compositional homogenization before coalescing via oriented attachment into well-defined nanoplates, a process critically modulated by interfacial energy. This work not only provides a solution to a long-standing synthetic bottleneck but also establishes TAC as a versatile paradigm for entropy-stabilized anisotropic nanomaterial design under mild conditions, opening new avenues for diverse functional applications.